Kiera Davis is going through tough times. She thinks her husband is having an affair, her teenage daughter is being rebellious, and Kiera's been having awful migraines, with bright flashes of light preluding them. She wants to think the migraines are normal, but she knows there's more beneath the surface-maybe connected to a haunting event in her past that she'd rather just forget about. Kiera's been living with a dark secret since high school, and feels the time is near for when she will be punished for it. Kiera feels like she's being haunted-by someone from her past, and by her vestigial twin whom she thinks is inside of her. Kiera ponders that her vestigial twin came to her to remind her of her past. When her friends are murdered, she has to face the truth. At each crime scene, witnesses say a woman who looked like Kiera was seen at each murder. But Kiera believes it couldn't have been her, because she was always in a different location than where the murder took place. As Kiera tries to put the pieces of this puzzle together, she tests her sanity, strength, and spirit as she tries to come to a logical decision through all of this.